The background of the invention will be discussed in two parts:
1. Field of the Invention
This invention relates to water and water vapor proofing and more particularly to the fastening and sealing of a geo-synthetic membrane under a concrete slab and/or to footings of an on grade or below grade foundation under any structure, to seal off water and water vapor at the joints between the foundation and slab and the areas directly under the slab foundation.
2. Description of the Related Art
Water and water vapor proofing of on grade or below grade concrete slab floor is an essential consideration during construction of residential, commercial and industrial structures. Evapo-transportation of molecular water from the subsoil to a water vapor state and transportation of the water vapor by vapor drive through the capillaries of the concrete foundation is a naturally occurring event. The water vapor molecules pick up the concrete salts through osmosis as they pass through the capillaries of the concrete and then pass through the carbonated cement paste of the concrete foundation to escape into the atmosphere of the structure. When water vapor molecules encounter a non-permeable or sufficiently dense structure the water vapor molecules convert back to water molecules. Since the water vapor molecules carried the salts of the concrete, the water molecules have an increase in pH to as high as 14. This combination of elevated water vapor transmission through the concrete foundation and the resulting increase in the pH of the water molecules presents the leading cause of adhesive, flooring and coating failures for above grade and below grade concrete slabs. These failures contribute floor covering problems such as adhesion loss, warping, peeling, buckling, staining, offensive odors and mold growth.
Traditionally, newly constructed structures require a moisture/vapor barrier such as polyethylene sheeting that is placed directly under an on grade or below grade concrete floor slabs. However, these polyethylene liners alone are inadequate in restriction of water and water vapor through concrete floor slabs for at least the following reasons:
1) Water/vapor will pass through the lap seams of the sheeting.
2) Water/vapor will pass through plumbing/electrical openings of on grade foundations.
3) Water/vapor will pass through the perimeter and interior of the foundation and throughout the plumbing and electrical trenches.
4) The durability of polyethylene sheeting under on grade foundations as a water/vapor barrier is questionable in that it cannot withstand the normal construction activities surrounding on grade or below grade foundation installation, i.e., it will puncture under normal foot traffic.
Another consideration is that water vapor molecules can pass through standard 6 to 10 mil polyethylene sheeting, which is the minimum requirement specified by the Uniform Building Code.
The prior art includes various approaches for providing a barrier to moisture permeation from the subsoil to above-slab coverings. One such approach is disclosed in U.S. Pat. No. 6,189,279, entitled Floating Floor Underlay, issued to Fiehtl on Feb. 20, 2001, that discloses a composite underlay product for a floating floor. This product is made from a vinyl film (like polyethylene) that creates a moisture impermeable underlay when laid over a wood or concrete sub-floor. The seams between butting sheets of the underlay are sealed with moisture impermeable tape. Another prior art patent is U.S. Pat. No. 5,376,429, entitled Laminated Water Stop Bentonite and Bentones, issued to Mcgroarty on Dec. 27, 1994, that discloses a water/water vapor barrier between the concrete footing and slab using a strip of Bentonite tape for a seal, the seal installed without changes to the concrete installation.
Thus, in view of the known prior art, an apparatus and method is needed that will provide an improved water/water vapor barrier that prevents permeation of water/water vapor through an on grade or below grade floor concrete floor slab. Applicants' invention provides such a barrier. The invention provides means for sealing of polyethylene liners at termination points as well as a water/water vapor seal barrier at the cold joints between the footing and slab that restricts intrusion of gases, vapors, liquids and insects without requiring revised construction practices, other than the wet setting of the water/water vapor seal into the concrete footing or direct placement within the concrete form work.